Anti-reflective film

ABSTRACT

The present invention relates to an anti-reflective film exhibiting one or more peaks at a scattering vector (qmax) of 0.0758 to 0.1256 nm−1, in a graph showing a log value of scattering intensity to a scattering vector defined in small-angle X-ray scattering.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the national stage of International Application No.PCT/KR2017/002583 filed on Mar. 9, 2017, and claims the benefit ofKorean Application No. 10-2016-0028468 filed on Mar. 9, 2016, KoreanPatent Application No. 10-2016-0029336 filed on Mar. 11, 2016, KoreanPatent Application No. 10-2016-0030395 filed on Mar. 14, 2016, andKorean Patent Application No. 10-2017-0029959 filed on Mar. 9, 2017, allof which are hereby incorporated by reference in their entirety for allpurposes as if fully set forth herein.

FIELD OF THE INVENTION

The present invention relates to an anti-reflective film, and morespecifically, to an anti-reflective film that has low reflectance andhigh light transmittance, and can simultaneously realize high scratchresistance and an anti-pollution property, and can increase screensharpness of a display device.

BACKGROUND OF THE INVENTION

In general, flat panel display devices such as a PDP, an LCD, etc., areequipped with an anti-reflective film so as to minimize reflection ofincident light from the outside.

Methods for minimizing the reflection of light include a method ofdispersing a filler such as inorganic fine particles, etc. in a resin,coating it on a substrate film, and imparting unevenness (anti-glare: AGcoating) thereto, a method of using light interference by formingmultiple layers having different refractive indexes on a substrate film(anti-reflective; AR coating), a method of using them together, etc.

Among them, in the case of the AG coating, although the absolute amountof reflected light is equivalent to common hard coatings, a lowreflection effect can be obtained by reducing the amount of lightentering the eyes using light scattering through unevenness. However,since the AG coating lowers screen sharpness due to the surfaceunevenness, recently, many studies on the AR coating are progressing.

As a film using the AR coating, those having a multi-layered structurein which a hard coating layer (high refractive index layer), a lowreflective coating layer, etc. are stacked on a substrate film are beingcommercialized. However, since the method of forming multiple layersseparately conducts the processes of forming each layer, it has adisadvantage in terms of lowered scratch resistance due to weakinterlayer adhesion (interface adhesion).

Previously, in order to improve scratch resistance of the low refractivelayer included in the anti-reflective film, a method of adding variousparticles of a nanometer size (for example, silica, alumina, zeolite,etc.) was mainly attempted. However, when using nanometer-sizedparticles, it was difficult to simultaneously increase scratchresistance while lowering the reflectance of the low refractive layer,and due to the nanometer-sized particles, the anti-pollution property ofthe surface of the low refractive layer was significantly deteriorated.

Accordingly, in order to reduce the absolute reflection amount ofincident light from the outside and improve the anti-pollution propertyas well as scratch resistance of the surface, many studies are beingprogressed, but the resulting property improvement degree isunsatisfactory.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

It is an object of the present invention to provide an anti-reflectivefilm that has low reflectance and high light transmittance, that cansimultaneously realize high scratch resistance and an anti-pollutionproperty, and can increase screen sharpness of a display device.

Technical Solution

An anti-reflective film exhibiting one or more peaks at a scatteringvector (q_(max)) of 0.0758 to 0.1256 nm⁻¹, in a graph showing the logvalue of scattering intensity to a scattering vector defined insmall-angle X-ray scattering, is provided herein.

Hereinafter, an anti-reflective film according to specific embodimentsof the invention will be explained in detail.

As used herein, a photopolymerizable compound commonly designates acompound that causes a polymerization reaction if light, for example,visible rays or ultraviolet rays, is irradiated thereto.

A fluorine-containing compound means a compound including at least onefluorine atom in the compound.

Further, (meth)acryl includes both acryl and methacryl.

In addition, (co)polymer includes both copolymer and homopolymer.

Also, silica hollow particles mean silica particles derived from asilicon compound or an organosilicon compound, wherein an empty spaceexists on the surface and/or inside of the silica particles.

According to one embodiment of the present invention, an anti-reflectivefilm exhibiting one or more peaks at a scattering vector (q_(max)) of0.0758 to 0.1256 nm⁻¹, in a graph showing a log value of scatteringintensity to a scattering vector defined in small-angle X-rayscattering, is provided.

The present inventors progressed studies on an anti-reflective film,confirmed through experiments that an anti-reflective film fulfillingthe requirement of exhibiting one or more peaks at a scattering vector(q_(max)) of 0.0758 to 0.1256 nm⁻¹, in a graph showing the log value ofscattering intensity to a scattering vector defined in small-angle X-rayscattering, has low reflectance and high light transmittance, and cansimultaneously realize high scratch resistance and an anti-pollutionproperty, and completed the present invention.

Specifically, whether or not an anti-reflective film may exhibit one ormore peaks of the log value of scattering intensity at a scatteringvector (q_(max)) of 0.0758 to 0.1256 nm⁻¹, in a graph showing the logvalue of scattering intensity to a scattering vector defined insmall-angle X-ray scattering, may be related to the internal structureof the anti-reflective film, for example, the average distance betweenthe organic or inorganic particles included in the anti-reflective film.

An anti-reflective film fulfilling the requirement of exhibiting one ormore peaks at a scattering vector (q_(max)) of 0.0758 to 0.1256 nm⁻¹, ina graph showing the log value of scattering intensity to a scatteringvector defined in small-angle X-ray scattering, can maintain anoptimized refractive index value, and thus, can realize low reflectance.

For example, if an anti-reflective film exhibits a peak at a scatteringvector of less than 0.0758 nm⁻¹ in a graph showing the log value ofscattering intensity to a scattering vector defined in small-angle X-rayscattering, the refractive index of the anti-reflective film mayincrease because of the excessive distance between the organic orinorganic particles included in the anti-reflective film, etc., and thusthe reflectance may also largely increase.

Meanwhile, if a peak first appears in a scattering vector of greaterthan 0.1256 nm⁻¹ in a graph showing the log value of scatteringintensity to a scattering vector defined in small-angle X-rayscattering, the distance between the organic or inorganic particlesincluded in the anti-reflective film may become too small, and thus theillumination of the anti-reflective film may increase and the scratchresistance and anti-pollution property may be deteriorated.

The peak is an extreme value at which the log value of scatteringintensity appears upwardly convex, in a graph showing the log value ofscattering intensity to a scattering vector defined in small-angle X-rayscattering. Such an extreme value or inflection point may be a point atwhich scattering is maximized by the arrangement of the organic orinorganic particles included in the anti-reflective film.

As explained above, the anti-reflective film of the embodiment mayexhibit one or more peaks at a scattering vector (q_(max)) of 0.0758 to0.1256 nm⁻¹, in a graph showing the log value of scattering intensity toa scattering vector defined in small-angle X-ray scattering. Morespecifically, the range of the scattering vector (q_(max)) of 0.0758 to0.1256 nm⁻¹, in a graph showing the log value of scattering intensity toa scattering vector defined in the small-angle X-ray scattering of theanti-reflective film of the embodiment, may be a point at which a peakof the log value of scattering intensity to the scattering vector firstappears.

The scattering vector defined in small-angle X-ray scattering is definedby the following Equation 1.q=4π sin θ/λ  [Equation 1]

In Equation 1, q is a scattering vector, θ is a ½ value of a scatteringangle, and λ is a wavelength of irradiated X-rays.

Specifically, the small-angle X-ray scattering means a transmission modeor grazing incidence small-angle X-ray scattering, and for example, maybe measured by irradiating X-rays of a wavelength of 0.63 Å to 1.54 Å toan anti-reflective film with a size of 1 cm*1 cm (width*length) at adistance of 4 m.

For example, small angle X-ray scattering (SAXS) may be achieved bytransmitting X-rays through a sample at the 4C beam line of a PohangAccelerator and measuring scattering intensity according to thescattering vector (q). More specifically, the small angle scatteringmeasurement may be conducted by placing a sample at a location about 4 maway from a detector and sending X-rays thereto, wherein X-rays having avertical size of 0.023 mm and a horizontal size of 0.3 mm may be used,and as the detector, a 2D mar CCD may be used. Further, the scattered 2Ddiffraction pattern is obtained as an image, and through calibrationusing a sample-to-detector distance obtained through a standard sample,and a circular average, scattering intensity according to the scatteringvector (q) may be converted.

Meanwhile, the requirement of exhibiting one or more peaks at ascattering vector (q_(max)) of 0.0758 to 0.1256 nm⁻¹, in a graph showingthe log value of scattering intensity to a scattering vector defined insmall-angle X-ray scattering, may be achieved by controlling theproperties of the anti-reflective film such as the components includedin the anti-reflective film, optical properties, surface properties,internal properties, etc.

For example, the anti-reflective film may include a hard coating layer,and a low refractive layer including a binder resin and hollow inorganicnanoparticles and solid inorganic nanoparticles dispersed in the binderresin.

Specifically, in the anti-reflective film, near the interface betweenthe hard coating layer and the low refractive layer, the solid inorganicnanoparticles may be more distributed than the hollow inorganicnanoparticles.

Previously, in order to increase scratch resistance of ananti-reflective film, inorganic particles were added in an excessamount, which had a limit in increasing scratch resistance of ananti-reflective film, and had a problem of deterioration of reflectanceand anti-pollution properties.

To the contrary, when hollow inorganic nanoparticles and solid inorganicnanoparticles are distributed so as to be distinguished from each otherin the low refractive layer included in the anti-reflective film, highscratch resistance and an anti-pollution property can be simultaneouslyrealized while having low reflectance and high light transmittance.

Specifically, when solid inorganic nanoparticles are mainly distributednear the interface between the hard coating layer and the low refractivelayer and hollow inorganic nanoparticles are mainly distributed to theopposite side in the low refractive layer of the anti-reflective film,lower reflectance compared to the reflectance that could be previouslyobtained using inorganic particles can be achieved, and the lowrefractive layer can simultaneously realize significantly improvedscratch resistance and anti-pollution properties.

As explained above, by fulfilling the requirement of exhibiting one ormore peaks at a scattering vector (q_(max)) of 0.0758 to 0.1256 nm⁻¹ ina graph showing the log value of scattering intensity to a scatteringvector defined at small-angle X-ray scattering, the anti-reflective filmhas low reflectance and high light transmittance, and can simultaneouslyrealize high scratch resistance and anti-pollution properties.

As explained above, the low refractive layer includes the binder resinand hollow inorganic nanoparticles and solid inorganic nanoparticlesdispersed in the binder resin, and may be formed on one side of the hardcoating layer, wherein 70 vol % or more of the total solid inorganicnanoparticles may exist within 50% of the total thickness of the lowrefractive layer from the interface between the hard coating layer andthe low refractive layer.

The description that 70 vol % or more of the total solid inorganicnanoparticles exist in a specific region means that in the cross-sectionof the low refractive layer, most of the solid inorganic nanoparticlesexist in the specific region, and specifically, 70 vol % or more of thetotal solid inorganic nanoparticles can be confirmed by measuring thevolume of the total solid inorganic nanoparticles.

Whether or not the hollow inorganic nanoparticles and the solidinorganic nanoparticles are present in specific regions may bedetermined by whether each of the hollow inorganic nanoparticles or eachof the solid inorganic nanoparticles is present in the specific region,except for particles present on an interface of the specific region.

Further, as explained above, in the low refractive layer, hollowinorganic nanoparticles may be mainly distributed to the opposite sideof the interface between the hard coating layer and the low refractivelayer, and specifically, 30 vol % or more, 50 vol % or more, or 70 vol %or more of the total hollow inorganic nanoparticles may exist fartherthan the total solid inorganic nanoparticles, in the thickness directionof the low refractive layer from the interface between the hard coatinglayer and the low refractive layer.

More specifically, 70 vol % or more of the total solid inorganicnanoparticles may exist within 30% of the total thickness of the lowrefractive layer from the interface between the hard coating layer andthe low refractive layer. In addition, 70 vol % or more of the totalhollow inorganic nanoparticles may exist in a region exceeding 30% ofthe total thickness of the low refractive layer from the interfacebetween the hard coating layer and the low refractive layer.

By mainly distributing solid inorganic nanoparticles near the interfacebetween the hard coating layer and the low refractive layer and mainlydistributing hollow inorganic nanoparticles to the opposite side of theinterface in the low refractive layer of the anti-reflective film, 2 ormore parts or 2 or more layers having different refractive indexes maybe formed in the low refractive layer, and thus the reflectance of theanti-reflective film may be lowered.

The specific distribution of the solid inorganic nanoparticles andhollow inorganic nanoparticles in the low refractive layer may beobtained by controlling the density difference between the solidinorganic nanoparticles and the hollow inorganic nanoparticles andcontrolling the drying temperature of a photocurable resin compositionfor forming a low refractive layer including the two kinds ofnanoparticles, in the preparation method described below.

Specifically, the solid inorganic nanoparticles may have 0.50 g/cm³ ormore higher density than the hollow inorganic nanoparticles, and thedensity difference between the solid inorganic nanoparticles and thehollow inorganic nanoparticles may be 0.50 g/cm³ to 1.50 g/cm³, or 0.60g/cm³ to 1.00 g/cm³. Due to such a density difference, in the lowrefractive layer formed on the hard coating layer, the solid inorganicnanoparticles may be positioned nearer to the hard coating layer.However, as confirmed in the preparation method and examples, etc.described below, despite the density difference between the two kinds ofparticles, predetermined drying temperature and time should be appliedso as to realize the above-explained distribution aspect of particles inthe low refractive layer.

In case the solid inorganic nanoparticles are mainly distributed nearthe interface between the hard coating layer and the low refractivelayer and the hollow inorganic nanoparticles are mainly distributed tothe opposite side of the interface in the low refractive layer of theanti-reflective film, lower reflectance than the reflectance previouslyobtained using inorganic particles can be realized. Specifically, theanti-reflective film may exhibit mean reflectance of 0.7% or less, 0.50to 0.7%, 0.60% to 0.70%, or 0.62% to 0.67% in the visible lightwavelength region of 380 nm to 780 nm.

Meanwhile, in the anti-reflective film of the embodiment, the lowrefractive layer may include a first layer including 70 vol % or more ofthe total solid inorganic nanoparticles and a second layer including 70vol % or more of the total hollow inorganic nanoparticles, and the firstlayer may be positioned nearer to the interface between the hard coatinglayer and the low refractive layer than the second layer.

As explained above, in the low refractive layer of the anti-reflectivefilm, solid inorganic nanoparticles are mainly distributed near theinterface between the hard coating layer and the low refractive layerand hollow inorganic nanoparticles are mainly distributed to theopposite side of the interface, and the regions where the solidinorganic nanoparticles and the hollow inorganic nanoparticles arerespectively mainly distributed may form separate layers that arevisibly confirmed in the low refractive layer.

Further, the first layer including 70 vol % or more of the total solidinorganic nanoparticles may be positioned within 50% of the totalthickness of the low refractive layer from the interface between thehard coating layer and the low refractive layer. More specifically, thefirst layer including 70 vol % or more of the total solid inorganicnanoparticles may exist within 30% of the total thickness of the lowrefractive layer from the interface between the hard coating layer andthe low refractive layer.

As explained above, in the low refractive layer, the hollow inorganicnanoparticles may be mainly distributed to the opposite side of theinterface between the hard coating layer and the low refractive layer,and specifically, 30 vol % or more, 50 vol % or more, or 70 vol % ormore of the hollow inorganic nanoparticles may exist farther than thesolid inorganic nanoparticles, in the thickness direction of the lowrefractive layer from the interface between the hard coating layer andthe low refractive layer. Thus, as explained above, the first layer maybe positioned nearer to the interface between the hard coating layer andthe low refractive layer, than the second layer.

As explained above, it can be visibly confirmed that the first layer andthe second layer where the solid inorganic nanoparticles and the hollowinorganic nanoparticles are mainly distributed, respectively, exist inthe low refractive layer. For example, it can be visibly confirmed usinga transmission electron microscope, a scanning electron microscope, etc.that the first layer and the second layer respectively exist in the lowrefractive layer, and the ratio of the solid inorganic nanoparticles andthe hollow inorganic nanoparticles that are distributed in the firstlayer and the second layer, respectively, in the low refractive layercan also be confirmed.

Meanwhile, each of the first layer including 70 vol % or more of thetotal solid inorganic nanoparticles and the second layer including 70vol % or more of the total hollow inorganic nanoparticles may sharecommon optical properties in one layer, and thus can be defined as onelayer.

More specifically, the first layer and the second layer respectivelyhave specific Cauchy parameters A, B, and C, when fitting thepolarization ellipticity measured by ellipsometry to a Cauchy model ofthe following Equation 1, and thus the first layer and the second layermay be distinguished from each other. Further, since the thicknesses ofthe first layer and the second layer may be derived through the fittingof the polarization ellipticity measured by ellipsometry to a Cauchymodel of the following Equation 1, the first layer and the second layercan be defined in the low refractive layer.

$\begin{matrix}{{n(\lambda)} = {A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1, n(λ) is a refractive index at a λ wavelength, λ is therange of 300 nm to 1800 nm, and A, B, and C are Cauchy parameters.

Meanwhile, the Cauchy parameters A, B, and C derived when fitting thepolarization ellipticity measured by ellipsometry to a Cauchy model ofEquation 1 may be the mean values in one layer. Thus, in case aninterface exists between the first layer and the second layer, a regionwhere the Cauchy parameters A, B, and C of the first layer and thesecond layer overlap may exist. However, even in this case, thethicknesses and the locations of the first layer and the second layermay be specified according to the regions satisfying the mean values ofCauchy parameters A, B, and C of the first layer and the second layer.

For example, for the first layer included in the low refractive layer,when fitting the polarization ellipticity measured by ellipsometry to aCauchy model of Equation 1, the requirements that A is 1.0 to 1.65, B is0.0010 to 0.0350, and C is 0 to 1*10⁻³ can be fulfilled, and for thefirst layer included in the low refractive layer, the requirements thatA is 1.30 to 1.55, 1.40 to 1.52, or 1.491 to 1.511, B is 0 to 0.005, 0to 0.00580, or 0 to 0.00573, and C is 0 to 1*10⁻³, 0 to 5.010⁻⁴, or 0 to4.135210⁻⁴ can be fulfilled.

For the second layer included in the low refractive layer, when fittingthe polarization ellipticity measured by ellipsometry to a Cauchy modelof Equation 1, the requirements that A is 1.0 to 1.50, B is 0 to 0.007and C is 0 to 1*10⁻³ can be fulfilled, and for the second layer includedin the low refractive layer, the requirements that A is 1.10 to 1.40,1.20 to 1.35, or 1.211 to 1.349, B is 0 to 0.007, 0 to 0.00550, or 0 to0.00513, and C is 0 to 110⁻³, 0 to 5.010⁻⁴, or 0 to 4.8685*10⁻⁴ can befulfilled.

Meanwhile, in the anti-reflective film of the above-explainedembodiment(s), the first layer and the second layer included in the lowrefractive layer may have different ranges of refractive indexes.

More specifically, the first layer included in the low refractive layermay have a refractive index of 1.420 to 1.600, 1.450 to 1.550, 1.480 to1.520, or 1.491 to 1.511, at 550 nm. The second layer included in thelow refractive layer may have a refractive index of 1.200 to 1.410,1.210 to 1.400, or 1.211 to 1.375, at 550 nm.

The refractive index may be measured by commonly known methods, and forexample, for each of the first layer and the second layer included inthe low refractive layer, a refractive index at 550 nm can be calculatedand determined using elliptic polarization measured at 380 nm to 1000 nmand a Cauchy model.

The solid inorganic nanoparticles mean particles that have a maximumdiameter of 100 nm or less, inside of which an empty space does notexist.

Further, the hollow inorganic nanoparticles mean particles that have amaximum diameter of 200 nm or less, on the surface and/or inside ofwhich an empty space exists.

The solid inorganic nanoparticles may have a diameter of 0.5 to 100 nm,or 1 to 30 nm.

The hollow inorganic nanoparticles may have a diameter of 1 to 200 nm,or 10 to 100 nm.

The diameters of the solid inorganic nanoparticles and the hollowinorganic nanoparticles may mean the longest diameters confirmed in thecross-sections of the particles.

Meanwhile, the solid inorganic nanoparticles and the hollow inorganicnanoparticles may respectively contain one or more reactive functionalgroups selected from the group consisting of a (meth)acrylate group, anepoxide group, a vinyl group, and a thiol group on the surface. As thesolid inorganic nanoparticles and the hollow inorganic nanoparticlesrespectively contain the above-explained reactive functional groups onthe surfaces, the low refractive layer may have a higher cross-linkingdegree, thus securing more improved scratch resistance andanti-pollution properties.

Meanwhile, the above-explained low refractive layer may be prepared froma photocurable coating composition including a photopolymerizablecompound, a fluorine-containing compound including a photoreactivefunctional group, hollow inorganic nanoparticles, solid inorganicnanoparticles, and a photoinitiator.

Thus, the binder resin included in the low refractive layer may includea (co)polymer of photopolymerizable compounds and a cross-linked(co)polymer of fluorine-containing compounds including photoreactivefunctional groups.

The photopolymerizable compound included in the photocurable coatingcomposition may form a substrate of the binder resin of the prepared lowrefractive layer. Specifically, the photopolymerizable compound mayinclude monomers or oligomers including (meth)acrylate or vinyl groups.More specifically, the photopolymerizable compound may include monomersor oligomers including one or more, two or more, or three or more(meth)acrylate or vinyl groups.

Specific examples of the monomers or oligomers including (meth)acrylatemay include pentaerythritol tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, dipentaerythritol penta(meth)acrylate,dipentaerythritol hexa(meth)acrylate, tripentaerythritolhepta(meth)acrylate, thrylene diisocyanate, xylene diisocyanate,hexamethylene diisocyanate, trimethylolpropane tri(meth)acrylate,trimethylolpropane polyethoxy tri(meth)acrylate, trimethylolpropanetrimethacrylate, ethylene glycol dimethacrylate, butanedioldimethacrylate, hexaethyl methacrylate, butyl methacrylate, or mixturesof two or more kinds thereof, or urethane modified acrylate oligomers,epoxide acrylate oligomers, etheracrylate oligomers, dendritic acrylateoligomers, or mixture of two or more kinds thereof. Here, it ispreferable that the molecular weight of the oligomer is 1000 to 10,000.

Specific examples of the monomers or oligomers including vinyl groupsmay include divinylbenzene, styrene, or paramethylstyrene.

Although the content of the photopolymerizable compound in thephotocurable coating composition is not particularly limited, thecontent of the photopolymerizable compound in the solid content of thephotocurable coating composition may be 5 to 80 wt % considering themechanical properties of the finally prepared low refractive layer oranti-reflective film, etc. The solid content of the photocurable coatingcomposition means only solid components excluding liquid components, forexample, organic solvents, etc. that may be optionally included asdescribed below, in the photocurable coating composition.

Meanwhile, the photocurable coating composition may further includefluorine-based (meth)acrylate-based monomers or oligomers, in additionto the above-explained monomers or oligomers. In case the photocurablecoating composition further includes fluorine-based (meth)acrylate-basedmonomers or oligomers, the weight ratio of the fluorine-based(meth)acrylate-based monomers or oligomers to the monomer or oligomersincluding (meth)acrylate or vinyl groups may be 0.1% to 10%.

Specific examples of the fluorine-based (meth)acrylate-based monomers oroligomers may include one or more compounds selected from the groupconsisting of the following Chemical Formulas 1 to 5.

In Chemical Formula 1, R¹ is a hydrogen group or a C1-6 alkyl group, ais an integer of 0 to 7, and b is an integer of 1 to 3.

In Chemical Formula 2, c is an integer of 1 to 10.

In Chemical Formula 3, d is an integer of 1 to 11.

In Chemical Formula 4, e is an integer of 1 to 5.

In Chemical Formula 5, f is an integer of 4 to 10.

Meanwhile, in the low refractive layer, a part derived from afluorine-containing compound including a photoreactive functional groupmay be included.

In the fluorine-containing compound including a photoreactive functionalgroup, one or more photoreactive functional groups may be included orsubstituted, wherein the photoreactive functional group means afunctional group capable of participating in a polymerization reactionby the irradiation of light, for example, by the irradiation of visiblerays or UV. The photoreactive functional group may include variousfunctional groups known to be capable of participating in apolymerization reaction by the irradiation of light, and for example,may include a (meth)acrylate group, an epoxide group, a vinyl group or athiol group.

Each fluorine-containing compound including a photoreactive functionalgroup may have a weight average molecular weight (weight averagemolecular weight in terms of polystyrene, measured by GPC method) of2000 to 200,000, and preferably 5000 to 100,000.

If the weight average molecular weight of the fluorine-containingcompound including a photoreactive functional group is too small, thefluorine-containing compounds may not be uniformly and effectivelyarranged on the surface of the photocurable coating composition and maybe positioned inside of the finally prepared low refractive layer, andthus the anti-pollution property of the surface of the low refractivelayer may be deteriorated and the cross-linking density of the lowrefractive layer may be lowered, and thus the mechanical properties suchas total strength, scratch resistance, etc. may be deteriorated.

Further, if the weight average molecular weight of thefluorine-containing compound including a photoreactive functional groupis too high, compatibility with other components in the photocurablecoating composition may be lowered, and thus haze of the finallyprepared low refractive layer may increase or light transmittance maydecrease, and strength of the low refractive layer may also be lowered.

Specifically, the fluorine-containing compound including a photoreactivefunctional group may include: i) aliphatic compounds or alicycliccompounds substituted by one or more photoreactive functional groups, inwhich at least one carbon is substituted by one or more fluorine atoms;ii) heteroaliphatic compounds or heteroalicyclic compounds substitutedby one or more photoreactive functional groups, in which at least onehydrogen is substituted by fluorine, and at least one carbon issubstituted by silicon; iii) polydialkyl siloxane-based polymers (forexample, polydimethyl siloxane-based polymers) substituted by one ormore photoreactive functional groups, in which at least one silicon issubstituted by one or more fluorine atoms; and iv) polyether compoundssubstituted by one or more photoreactive functional groups, in which atleast one hydrogen is substituted by fluorine, or mixtures or copolymersof two or more kinds of i) to iv).

The photocurable coating composition may include, based on 100 parts byweight of the photopolymerizable compound, 20 to 300 parts by weight ofthe fluorine-containing compound including a photoreactive functionalgroup.

If the fluorine-containing compound including a photoreactive functionalgroup is added in an excess amount based on the photopolymerizablecompound, coatability of the photocurable coating composition may bedeteriorated or a low refractive layer obtained from the photocurablecoating composition may not have sufficient durability or scratchresistance. Further, if the amount of the fluorine-containing compoundincluding a photoreactive functional group is too small based on thephotopolymerizable compound, a low refractive layer obtained from thephotocurable coating composition may not have sufficient mechanicalproperties such as anti-pollution property, scratch resistance, etc.

The fluorine-containing compound including a photoreactive functionalgroup may further include silicon or a silicon compound. That is, thefluorine-containing compound including a photoreactive functional groupmay optionally contain silicon or a silicon compound therein, andspecifically, the content of silicon in the fluorine-containing compoundincluding a photoreactive functional group may be 0.1 to 20 wt %.

The silicon included in the fluorine-containing compound including aphotoreactive functional group may increase compatibility with othercomponents included in the photocurable coating composition, thuspreventing generation of haze in the finally prepared refractive layer,thereby increasing transparency. Meanwhile, if the content of siliconbecomes too high in the fluorine-containing compound including aphotoreactive functional group, compatibility between thefluorine-containing compound and the other components included in thephotocurable coating composition may be rather deteriorated, and thusthe finally prepared low refractive layer or anti-reflective film maynot have sufficient light transmittance or anti-reflective performance,and the anti-pollution property of the surface may also be deteriorated.

The low refractive layer may include, based on 100 parts by weight ofthe (co)polymer of the photopolymerizable compounds, 10 to 400 parts byweight of the hollow inorganic nanoparticles and 10 to 400 parts byweight of the solid inorganic nanoparticles.

If the content of the hollow inorganic nanoparticles and the solidinorganic nanoparticles becomes excessive in the low refractive layer,the hollow inorganic nanoparticles and the solid inorganic nanoparticlesmay exist mixedly without sufficient phase separation therebetween inthe preparation process of the low refractive layer, and thusreflectance may increase, and surface unevenness may be excessivelygenerated, thus deteriorating the anti-pollution property. Further, ifthe content of the hollow inorganic nanoparticles and the solidinorganic nanoparticles is too small in the low refractive layer, it maybe difficult for the majority of the solid inorganic particles to bepositioned near the interface between the hard coating layer and the lowrefractive layer, and the reflectance of the low refractive layer maysignificantly increase.

The low refractive layer may have a thickness of 1 to 300 nm, or 50 to200 nm.

Meanwhile, as the hard coating layer, commonly known hard coating layersmay be used without specific limitations.

One example of the hard coating layer may include a hard coating layerincluding a binder resin including a photocurable resin and organic orinorganic fine particles dispersed in the binder resin.

The photocurable resin included in the hard coating layer may be apolymer of photocurable compounds capable of inducing a polymerizationreaction if light such as UV, etc., is irradiated, as is commonly knownin the art. Specifically, the photocurable resin may include one or moreselected from the group consisting of: reactive acrylate oligomers suchas a urethane acrylate oligomer, an epoxide acrylate oligomer, apolyester acrylate, and a polyether acrylate; and multifunctionalacrylate monomers such as dipentaerythritol hexaacrylate,dipentaerythritol hydroxy pentaacrylate, pentaerythritol tetraacrylate,pentaerythritol triacrylate, trimethylene propyl triacrylate,propoxylated glycerol triacrylate, trimethylpropane ethoxy triacrylate,1,5-hexanediol acrylate, propoxylated glycerol triacrylate, tripropyleneglycol diacrylate, and ethylene glycol diacrylate.

Although the particle diameter of the organic or inorganic fineparticles is not specifically limited, for example, the organic fineparticles may have a particle diameter of 1 to 10 μm, and the inorganicfine particles may have a particle diameter of 1 to 500 nm, or 1 to 300nm. The particle diameter of the organic or inorganic fine particles maybe defined as a volume average particle diameter.

Further, although specific examples of the organic or inorganic fineparticles included in the hard coating film are not limited, forexample, the organic or inorganic fine particles may be organic fineparticles selected from the group consisting of acryl-based resins,styrene-based resins, epoxide resins, and nylon resins, or inorganicfine particles selected from the group consisting of silicon oxide,titanium dioxide, indium oxide, tin oxide, zirconium oxide, and zincoxide.

The binder resin of the hard coating layer may further include a highmolecular weight (co)polymer with a weight average molecular weight of10,000 or more.

The high molecular weight (co)polymer may be one or more selected fromthe group consisting of a cellulose-based polymer, an acryl-basedpolymer, a styrene-based polymer, an epoxide-based polymer, anylon-based polymer, a urethane-based polymer, and a polyolefin-basedpolymer.

Another example of the hard coating film may include a hard coating filmincluding a binder resin of a photocurable resin, and an antistaticagent dispersed in the binder resin.

The photocurable resin included in the hard coating layer may be apolymer of photocurable compounds capable of inducing a polymerizationreaction by the irradiation of light such as UV, etc., as is commonlyknown in the art. However, preferably, the photocurable compound may bemultifunctional (meth)acrylate-based monomers or oligomers, wherein itis advantageous in terms of securing of the properties of the hardcoating layer that the number of (meth)acrylate-based functional groupsis 2 to 10, preferably 2 to 8, and more preferably 2 to 7. Morepreferably, the photocurable compound may be one or more selected fromthe group consisting of pentaerythritol tri(meth)acrylate,pentaerythritol tetra(meth)acrylate, dipentaerythritolpenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate,dipentaerythritol hepta(meth)acrylate, tripentaerythritolhepta(meth)acrylate, thrylene diisocyanate, xylene diisocyanate,hexamethylene diisocyanate, trimethylol propane tri(meth)acrylate, andtrimethylol propane polyethoxy tri(meth)acrylate.

The antistatic agent may be: a quaternary ammonium salt compound; apyridinium salt; a cationic compound having 1 to 3 amino groups; ananionic compound such as a sulfonic acid base, a sulfuric ester base, aphosphoric ester base, a phosphonic acid base, etc.; an amphotericcompound such as an amino acid-based, an amino sulfuric ester-basedcompound, etc.; a non-ionic compound such as an imino alcohol-basedcompound, a glycerin-based compound, a polyethylene glycol-basedcompound, etc.; an organometal compound such as a metal alkoxidecompound containing tin or titanium, etc.; a metal chelate compound suchas an acetylacetonate salt of the organometal compound, etc.; reactantsor polymerized products of two or more kinds of these compounds; ormixtures of two or more kinds of these compounds. Here, the quaternaryammonium salt compound may be a compound having one or more quaternaryammonium salt groups in the molecule, and a low molecular type or a highmolecular type may be used without limitations.

As the antistatic agent, a conductive polymer and metal oxide fineparticles may also be used. The conductive polymer may include aromaticconjugated poly(paraphenylene), heterocyclic conjugated polypyrrole,polythiophene, aliphatic conjugated polyacetylene, heteroatom-containingconjugated polyaniline, mixed conjugated poly(phenylene vinylene), amultichain type of conjugated compound which is a conjugated compoundhaving multiple conjugated chains in the molecule, a conductive complexin which a conjugated polymer chain is grafted on or block copolymerizedwith a saturated polymer, etc. The metal oxide fine particles mayinclude zinc oxide, antimony oxide, tin oxide, cerium oxide, indium tinoxide, indium oxide, aluminum oxide, antimony-doped tin oxide,aluminum-doped zinc oxide, etc.

The hard coating film including a binder resin of a photocurable resin,and an antistatic agent dispersed in the binder resin, may furtherinclude one or more compounds selected from the group consisting ofalkoxy silane-based oligomers and metal alkoxide-based oligomers.

Although the alkoxy silane-based compound may be one commonly used inthe art, preferably, it may include one or more compounds selected fromthe group consisting of tetramethoxysilane, tetraethoxysilane,tetraisopropoxysilane, methyltrimethoxysilane, methyltriethoxysilane,methacryloxypropyltrimethoxysilane, glycidoxy propyl trimethoxy silane,and glycidoxy propyl triethoxy silane.

The metal alkoxide-based oligomer may be prepared by the sol-gelreaction of a composition including a metal alkoxide-based compound andwater. The sol-gel reaction may be conducted by a similar method to theabove-explained preparation method of an alkoxy silane-based oligomer.

However, since the metal alkoxide-based compound may rapidly react withwater, the sol-gel reaction may be conducted by diluting the metalalkoxide-based compound in an organic solvent, and then slowly drippingwater thereto. At this time, considering the reaction efficiency, it ispreferable that the mole ratio of the metal alkoxide-based compound towater (based on metal ions) is controlled within a range of 3 to 170.

Here, the metal alkoxide-based compound may be one or more compoundsselected from the group consisting of titanium tetra-isopropoxide,zirconium isopropoxide, and aluminum isopropoxide.

The hard coating layer may have a thickness of 0.1 to 100 μm.

The anti-reflective film may further include a substrate bonded to theother side of the hard coating layer. Specific kinds or thicknesses ofthe substrate are not limited, and substrates known to be used in thepreparation of low refractive layers or anti-reflective films may beused without specific limitations.

Meanwhile, the anti-reflective film of the embodiment may be provided bya preparation method of an anti-reflective film including the steps of:applying a resin composition for forming a low refractive layerincluding a photocurable compound or a (co)polymer thereof, afluorine-containing compound including a photoreactive functional group,a photoinitiator, hollow inorganic nanoparticles, and solid inorganicnanoparticles on a hard coating layer, and drying at a temperature of 35to 100° C., or 40 to 80° C.; and photocuring the dried product of theresin composition.

Specifically, the anti-reflective film provided by the preparationmethod of an anti-reflective film distributes hollow inorganicnanoparticles and solid inorganic nanoparticles so as to bedistinguished from each other in the low refractive layer, therebysimultaneously realizing high scratch resistance and anti-pollutionproperties while having low reflectance and high light transmittance.

More specifically, the anti-reflective film includes: a hard coatinglayer; and a low refractive layer that is formed on one side of the hardcoating layer, and includes a binder resin, and hollow inorganicnanoparticles and solid inorganic nanoparticles dispersed in the binderresin, wherein 70 vol % or more of the total solid inorganicnanoparticles may exist within 50% of the total thickness of the lowrefractive layer from the interface between the hard coating layer andthe low refractive layer.

In addition, 30 vol % or more of the total hollow inorganicnanoparticles may exist farther than the total solid inorganicnanoparticles, in the thickness direction of the low-refraction layerfrom the interface between the hard coating layer and the low-refractionlayer.

Further, 70 vol % or more of the total solid inorganic nanoparticles mayexist within 30% of the total thickness of the low-refraction layer fromthe interface between the hard coating layer and the low-refractionlayer. Additionally, 70 vol % or more of the total hollow inorganicnanoparticles may exist at a region exceeding 30% of the total thicknessof the low-refraction layer from the interface between the hard coatinglayer and the low-refraction layer.

In the anti-reflective film provided by the above-described preparationmethod of an anti-reflective film, the low-refraction layer may includea first layer including 70 vol % or more of the total solid inorganicnanoparticles and a second layer including 70 vol % or more of the totalhollow inorganic nanoparticles, and the first layer may be positionednearer to the interface between the hard coating layer and thelow-refraction layer than the first layer.

The low refractive layer may be formed by applying a resin compositionfor forming a low refractive layer including a photocurable compound ora (co)polymer thereof, a fluorine-containing compound including aphotoreactive functional group, a photoinitiator, hollow inorganicnanoparticles, and solid inorganic nanoparticles on a hard coatinglayer, and drying at a temperature of 35 to 100° C., or 40 to 80° C.

If the temperature of drying the resin composition for forming a lowrefractive layer applied on a hard coating layer is less than 35° C.,the anti-pollution property of the formed low refractive layer may besignificantly deteriorated. Further, if the temperature of drying theresin composition for forming a low refractive layer applied on a hardcoating layer is greater than 100° C., the hollow inorganicnanoparticles and the solid inorganic nanoparticles may exist mixedlywithout sufficient phase separation therebetween, and thus the scratchresistance and anti-pollution properties of the low refractive layer maybe deteriorated and the reflectance may significantly increase.

In the process of drying the resin composition for forming a lowrefractive layer applied on the hard coating layer, by controlling thedensity difference between the solid inorganic nanoparticles and thehollow inorganic nanoparticles as well as the drying temperature, a lowrefractive layer having the above-explained properties may be formed.The solid inorganic nanoparticles may have 0.50 g/cm³ or more higherdensity than the hollow inorganic nanoparticles, and due to such adensity difference, the solid inorganic nanoparticles may be positionednearer to the hard coating layer in a low refractive layer formed on thehard coating layer.

Specifically, the solid inorganic nanoparticles may have a density of2.00 g/cm³ to 4.00 g/cm³, and the hollow inorganic nanoparticles mayhave a density of 1.50 g/cm³ to 3.50 g/cm³.

Meanwhile, the step of drying the resin composition for forming a lowrefractive layer applied on the hard coating layer at a temperature of35 to 100° C. may be conducted for 10 s to 5 min, or 30 s to 4 min.

If the drying time is too short, phase separation between the solidinorganic nanoparticles and the hollow inorganic nanoparticles may notsufficiently occur. To the contrary, if the drying time is too long, thelow refractive layer formed may erode the hard coating layer.

The low refractive layer may be prepared from a photocurable coatingcomposition including a photocurable compound or a (co)polymer thereof,a fluorine-containing compound including a photoreactive functionalgroup, hollow inorganic nanoparticles, solid inorganic nanoparticles,and a photoinitiator.

The low refractive layer may be obtained by applying the photocurablecoating composition on a predetermined substrate and photocuring theapplied substance. Specific kinds or thicknesses of the substrate arenot significantly limited, and any substrates known to be used for thepreparation of low refractive layers or anti-reflective films may beused without specific limitations.

For the application of the photocurable coating composition, commonlyused methods and apparatuses may be used without specific limitations,and for example, bar coating such as with a Meyer bar, etc., gravurecoating, 2 roll reverse coating, vacuum slot die coating, 2 rollcoating, etc. may be used.

The low refractive layer may have a thickness of 1 to 300 nm, or 50 to200 nm. Thus, the thickness of the photocurable coating compositionapplied on the predetermined substrate may be about 1 to 300 nm, or 50to 200 nm.

In the step of photocuring the photocurable coating composition, UV orvisible rays of a 200 to 400 nm wavelength may be irradiated, and theexposure amount may be 100 to 4000 mJ/cm². The exposure time is notspecifically limited, and may be appropriately changed according to theexposure apparatus used, the wavelength of irradiated light rays, or anexposure amount.

Further, in the step of photocuring the photocurable coatingcomposition, nitrogen purging, etc. may be conducted so as to apply anitrogen atmosphere condition.

The details of the photocurable compound, hollow inorganicnanoparticles, solid inorganic nanoparticles, and fluorine-containingcompound including a photoreactive functional group are as explainedabove.

The hollow inorganic nanoparticles and the solid inorganic nanoparticlesmay be respectively included in the composition as a colloidal phasedispersed in a predetermined dispersion medium. Each colloidal phaseincluding the hollow inorganic nanoparticles and the solid inorganicnanoparticles may include an organic solvent as a dispersion medium.

Each content of the hollow inorganic nanoparticles and the solidinorganic nanoparticles in a colloidal phase may be determinedconsidering each content range of the hollow inorganic nanoparticles andthe solid inorganic nanoparticles in the photocurable coatingcomposition or the viscosity of the photocurable coating composition,etc., and for example, each solid content of the hollow inorganicnanoparticles and the solid inorganic nanoparticles in the colloidalphase may be 5 to 60 wt %.

Here, as the organic solvent in the dispersion medium, alcohols such asmethanol, isopropyl alcohol, ethylene glycol, butanol, etc.; ketonessuch as methyl ethyl ketone, methyl isobutyl ketone, etc.; aromatichydrocarbons such as toluene, xylene, etc.; amides such asdimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc.; esterssuch as ethyl acetate, butyl acetate, gamma butyrolactone, etc.; etherssuch as tetrahydrofuran, 1,4-dioxane, etc.; or mixtures thereof may beincluded.

As the photopolymerization initiator, any compounds known to be usablein a photocurable resin composition may be used without significantlimitations, and specifically, a benzophenone-based compound, anacetophenone-based compound, a biimidazole-based compound, atriazine-based compound, an oxime-based compound, or mixtures of two ormore kinds thereof may be used.

The photopolymerization initiator may be used in the content of 1 to 100parts by weight, based on 100 parts by weigh of the photopolymerizablecompound. If the content of the photopolymerization initiator is toosmall, in the step of photocuring of the photocurable coatingcomposition, a material that is not cured in the photocuring step andremains may be generated. If the content of the photopolymerizationinitiator is too large, unreacted initiator may remain as an impurity ora cross-linking degree may be lowered, and thus the mechanicalproperties of the prepared film may be deteriorated or reflectance maysignificantly increase.

The photocurable coating composition may further include an organicsolvent.

Non-limiting examples of the organic solvent may include, for example,ketones, alcohols, acetates, ethers, and mixtures of two or more kindsthereof.

Specific examples of the organic solvent may include ketones such asmethyl ethyl ketone, methyl isobutyl ketone, acetylacetone, isobutylketone, etc.; alcohols such as methanol, ethanol, diacetone alcohol,n-propanol, i-propanol, n-butanol, i-butanol, t-butanol, etc.; acetatessuch as ethyl acetate, i-propyl acetate, polyethylene glycolmonomethylether acetate, etc.; ethers such as tetrahydrofuran, propyleneglycol monomethylether, etc.; and mixtures of two or more kinds thereof.

The organic solvent may be added when mixing the components included inthe photocurable coating composition, or each component may be addedwhile being dispersed in or mixed in the organic solvent. If the contentof the organic solvent in the photocurable coating composition is toosmall, flowability of the photocurable coating composition may bedeteriorated, and thus faults such as stripes, etc. may be generated inthe finally prepared film. If the organic solvent is excessively added,the solid content may decrease, and thus coating and film formation maynot be sufficiently achieved, thus deteriorating the properties orsurface property of the film, and generating faults in the process ofdrying and curing. Thus, the photocurable coating composition mayinclude an organic solvent such that the total solid concentration ofthe included components may become 1 to 50 wt %, or 2 to 20 wt %.

As the hard coating layer, a material known to be usable in ananti-reflective film may be used without specific limitations.

The components used for the formation of the hard coating layer are asexplained above with regard to the anti-reflective film of theembodiment.

For the application of the polymer resin composition for forming a hardcoating layer, commonly used methods and apparatuses may be used withoutspecific limitations, and for example, bar coating such as with a Meyerbar, etc., gravure coating, 2 roll reverse coating, vacuum slot diecoating, 2 roll coating, etc. may be used.

In the step of photocuring the polymer resin composition for forming ahard coating layer, UV or visible rays of a 200 to 400 nm wavelength maybe irradiated, wherein the exposure amount may preferably be 100 to 4000mJ/cm². The exposure time is not specifically limited, and may beappropriately changed according to the exposure apparatus used, thewavelength of irradiated light rays, or an exposure amount. Also, in thestep of photocuring the polymer resin composition for forming a hardcoating layer, nitrogen purging, etc. may be conducted so as to apply anitrogen atmosphere condition.

Advantageous Effects

According to the present invention, an anti-reflective film that has lowreflectance and high light transmittance, that can simultaneouslyrealize high scratch resistance and anti-pollution properties, and thatcan increase the screen sharpness of a display device, and a method forpreparing the anti-reflective film, are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the cross-sectional TEM image of the anti-reflective filmof Example 1.

FIG. 2 shows the cross-sectional TEM image of the anti-reflective filmof Example 2.

FIG. 3 shows the cross-sectional TEM image of the anti-reflective filmof Example 3.

FIG. 4 shows the cross-sectional TEM image of the anti-reflective filmof Example 4.

FIG. 5 shows the cross-sectional TEM image of the anti-reflective filmof Example 5.

FIG. 6 shows the cross-sectional TEM image of the anti-reflective filmof Example 6.

FIG. 7 shows the cross-sectional TEM image of the anti-reflective filmof Comparative Example 1.

FIG. 8 shows the cross-sectional TEM image of the anti-reflective filmof Comparative Example 2.

FIG. 9 shows the cross-sectional TEM image of the anti-reflective filmof Comparative Example 3.

FIG. 10 is a graph showing the log value of scattering intensity to ascattering vector defined in small angle scattering obtained by X-rayirradiation of the anti-reflective film of Example 1.

FIG. 11 is a graph showing the log value of scattering intensity to ascattering vector defined in small angle scattering obtained by X-rayirradiation of the anti-reflective film of Example 2.

FIG. 12 is a graph showing the log value of scattering intensity to ascattering vector defined in small angle scattering obtained by X-rayirradiation of the anti-reflective film of Example 3.

FIG. 13 is a graph showing the log value of scattering intensity to ascattering vector defined in small angle scattering obtained by X-rayirradiation of the anti-reflective film of Example 4.

FIG. 14 is a graph showing the log value of scattering intensity to ascattering vector defined in small angle scattering obtained by X-rayirradiation of the anti-reflective film of Example 5.

FIG. 15 is a graph showing the log value of scattering intensity to ascattering vector defined in small angle scattering obtained by X-rayirradiation of the anti-reflective film of Example 6.

FIG. 16 is a graph showing the log value of scattering intensity to ascattering vector defined in small angle scattering obtained by X-rayirradiation of the anti-reflective film of Comparative Example 1.

FIG. 17 is a graph showing the log value of scattering intensity to ascattering vector defined in small angle scattering obtained by X-rayirradiation of the anti-reflective film of Comparative Example 2.

FIG. 18 is a graph showing the log value of scattering intensity to ascattering vector defined in small angle scattering obtained by X-rayirradiation of the anti-reflective film of Comparative Example 3.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention will be explained in detail in the followingexamples. However, these examples are presented only as theillustrations of the present invention, and the scope of the presentinvention is not limited thereby.

PREPARATION EXAMPLE Preparation Example: Preparation of a Hard CoatingFilm

A salt type of antistatic hard coating liquid manufactured by KYOEISHACompany (solid content 50 wt %, product name:LJD-1000) was coated on atriacetyl cellulose film with a #10 Meyer bar and dried at 90° C. for 1min, and then irradiated by UV at 150 mJ/cm² to prepare a hard coatingfilm with a thickness of about 5 to 6 μm.

Examples 1 to 5: Preparation of an Anti-Reflective Film Examples 1 to 4

(1) Preparation of a Photocurable Coating Composition for Forming a LowRefractive Layer

Based on 100 parts by weight of pentaerythritol triacrylate (PETA), 281parts by weight of hollow silica nanoparticles (diameter: about 50 to 60nm, density: 1.96 g/cm³, manufactured by JSC Catalysts and ChemicalsLtd.), 63 parts by weight of solid silica nanoparticles (diameter: about12 nm, density: 2.65 g/cm³), 131 parts by weight of a firstfluorine-containing compound (X-71-1203M, ShinEtsu Chemical Co., Ltd.),19 parts by weight of a second fluorine-containing compound (RS-537, DICCorporation), and 31 parts by weight of an initiator (Irgacure 127, CibaCorporation) were diluted in a MIBK (methyl isobutyl ketone) solventsuch that the solid concentration became 3 wt %.

(2) Preparation of a Low Refractive Layer and an Anti-Reflective Film

On the hard coating film of the preparation example, the above-obtainedphotocurable coating composition was coated to a thickness of about 110to 120 nm with a #4 Meyer bar, and dried and cured using the temperatureand time as described in the following Table 1. During the curing, UV at252 mJ/cm² was irradiated to the dried coating under nitrogen purging.

Example 5

(1) Preparation of a Photocurable Coating Composition for Forming a LowRefractive Layer

Based on 100 parts by weight of trimethylolpropane triacrylate (TMPTA),268 parts by weight of hollow silica nanoparticles (diameter: about 50to 60 nm, density: 1.96 g/cm³, manufactured by JSC Catalysts andChemicals Ltd.), 55 parts by weight of solid silica nanoparticles(diameter: about 12 nm, density: 2.65 g/cm³), 144 parts by weight of afirst fluorine-containing compound (X-71-1203M, ShinEtsu Chemical Co.,Ltd.), 21 parts by weight of a second fluorine-containing compound(RS-537,DIC Corporation), and 31 parts by weight of an initiator(Irgacure 127, Ciba Corporation) were diluted in a MIBK (methyl isobutylketone) solvent such that the solid concentration became 3 wt %.

(2) Preparation of a Low Refractive Layer and an Anti-Reflective Film

On the hard coating film of the preparation example, the above-obtainedphotocurable coating composition was coated to a thickness of about 110to 120 nm with a #4 Meyer bar, and dried and cured using the temperatureand time as described in the following Table 1. During the curing, UV at252 mJ/cm² was irradiated to the dried coating under nitrogen purging.

TABLE 1 Drying Drying temperature time Example 1 40° C. 1 min Example 260° C. 1 min Example 3 80° C. 1 min Example 4 60° C. 2 min Example 5 60°C. 3 min

Example 6

(1) Preparation of a hard coating layer (HD2)

30 g of pentaerythritol triacrylate, 2.5 g of a high molecular weightcopolymer (BEAMSET 371, Arakawa Co. Ltd., Epoxy Acrylate, molecularweight 40,000), 20 g of methyl ethyl ketone, and 0.5 g of a levelingagent (Tego Wet 270) were uniformly mixed, and then 2 g of anacryl-styrene copolymer (volume average particle diameter: 2 μm,Manufacturing Company: Sekisui Plastic) with a refractive index of 1.525was added as fine particles to prepare a hard coating composition.

The above-obtained hard coating composition was coated on a triacetylcellulose film with a #10 Meyer bar and dried at 90° C. for 1 min. Thedried coating was irradiated by UV at 150 mJ/cm² to prepare a hardcoating layer with a thickness of 5 μm.

(2) Preparation of a Low Refractive Layer and an Anti-Reflective Film

Based on 100 parts by weight of pentaerythritol triacrylate (PETA), 135parts by weight of hollow silica nanoparticles (diameter: about 50 to 60nm, density: 1.96 g/cm³, manufactured by JSC Catalysts and ChemicalsLtd.), 88 parts by weight of solid silica nanoparticles (diameter: about12 nm, density: 2.65 g/cm³), 38 parts by weight of a firstfluorine-containing compound (X-71-1203M, ShinEtsu Chemical Co., Ltd.),11 parts by weight of a second fluorine-containing compound (RS-537,DICCorporation), and 7 parts by weight of an initiator (Irgacure 127, CibaCorporation) were diluted in a mixed solvent of MIBK (methyl isobutylketone):diacetone alcohol (DAA):isopropyl alcohol at a weight ratio of3:3:4 such that the solid concentration became 3 wt %, thus preparing aphotocurable coating composition for forming a low refractive layer.

On the above-prepared hard coating film (HD2), the above-obtainedphotocurable coating composition for forming a low refractive layer wascoated to a thickness of about 110 to 120 nm with a #4 Meyer bar, anddried and cured at a temperature of 60° C. for 1 min. During the curing,UV at 252 mJ/cm² was irradiated to the dried coating under nitrogenpurging.

COMPARATIVE EXAMPLES: PREPARATION OF AN ANTI-REFLECTIVE FILM ComparativeExample 1

An anti-reflective film was prepared by the same method as in Example 1,except that the photocurable coating composition for forming a lowrefractive layer was applied and dried at room temperature (25° C.).

Comparative Example 2

A photocurable coating composition for forming a low refractive layerwas prepared by the same method as in Example 1, except that 63 parts byweight of the solid silica nanoparticles used in Example 1 were replacedby 63 parts by weight of pentaerythritol triacrylate (PETA), and ananti-reflective layer was prepared by the same method as in Example 1.

Comparative Example 3

An anti-reflective film was prepared by the same method as in Example 5,except that the photocurable coating composition for forming a lowrefractive layer was applied and dried at 140° C.

Experimental Example: Measurement of the Properties of Anti-ReflectiveFilms

For the anti-reflective films obtained in the examples and comparativeexamples, the following experiments were conducted.

1. Measurement of Mean Reflectance of an Anti-Reflective Film

The mean reflectances of the ant-reflective films of the examples andcomparative examples at a visible light region (380 to 780 nm) weremeasured using Solidspec 3700 (SHIMADZU).

2. Measurement of Anti-Pollution Property

On the surface of the anti-reflective films obtained in the examples andcomparative examples, straight lines with a length of 5 cm were drawnwith a black felt pen, and rubbed with a clean wiper, and the number ofrubbing times at which the lines were erased was confirmed to measurethe anti-pollution property.

<Measurement Standard>

◯: The number of rubbing times at which the lines are erased is 10 orless

Δ: The number of rubbing times at which the lines are erased is 11 to 20

X: The number of rubbing times at which the lines are erased is greaterthan 20

3. Measurement of Scratch Resistance

While steel wool was loaded and allowed to go back and forth 10 times at27 rpm, the surfaces of the anti-reflective films obtained in theexamples and comparative examples were rubbed. The maximum load underwhich a scratch of 1 cm or less is observed as one or less with theunaided eye, was measured.

4. Measurement of Refractive Index

For the phase-separated regions of the low refractive layers obtained inthe examples, refractive indexes at 550 nm were calculated usingelliptic polarization at a wavelength of 380 nm to 1000 nm and using aCauchy model.

Specifically, for each low refractive layer obtained in the examples,using an apparatus of J. A. Woollam Co. M-2000, a 70° incidence anglewas applied and linear polarization was measured at a wavelength rangeof 380 to 1000 nm. The measured ellipsometry data (ψ, Δ) was fitted to aCauchy model of the following Equation 1 for Layer 1 and Layer 2 of thelow refractive layer such that MSE became 3 or less, using Complete EASEsoftware.

$\begin{matrix}{{n(\lambda)} = {A + \frac{B}{\lambda^{2}} + \frac{C}{\lambda^{4}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In Equation 1, n(λ) is a refractive index at a λ wavelength, Δ is arange of 300 to 1800 nm, and A, B, and C are Cauchy parameters.

5. Measurement of Scattering Intensity According to Scattering Vector inSmall Angle X-Ray Scattering

To a specimen of 1 cm*1 cm (width*length) obtained from eachanti-reflective film of the examples and comparative examples, X-rays ofa wavelength of 1.54 Å were irradiated at a distance of 4 m, thusmeasuring the scattering vector and scattering intensity.

Specifically, scattering intensity according to the scattering vector(q) was measured by transmitting X-rays through the specimen at a 4Cbeam line of a Pohang Accelerator. More specifically, small anglescattering measurement was conducted by placing the specimen at alocation about 4 m away from a detector and sending X-rays thereto,using X-rays with a vertical size of 0.023 mm and a horizontal size of0.3 mm, and using 2D mar CCD as a detector. The scattered 2D diffractionpattern was obtained as an image, which was converted into scatteringintensity according to the scattering vector (q) through calibrationusing a sample-to-detector distance obtained through a standard sample,and a circular average.q=4π sin θ/λ  [Equation 1]In Equation 1, q is a scattering vector, θ is a ½ value of a scatteringangle, and λ is the wavelength of irradiated X-rays.

Based on the above measurement results, a scattering vector (q_(max))value at which a first peak appears in a graph showing the log value ofscattering intensity according to the scattering vector defined in smallangle X-ray scattering, was calculated.

TABLE 2 Whether or Mean Scratch Anti- not phase reflectance resistancepollution separation qmax (%) (g) property occurs (nm-1) Example 1 0.63500 ◯ ◯ 0.12 Example 2 0.62 500 ◯ ◯ 0.121 Example 3 0.67 500 ◯ ◯ 0.119Example 4 0.64 500 ◯ ◯ 0.12 Example 5 0.65 500 ◯ ◯ 0.12 Example 6 0.67500 ◯ ◯ 0.106 Comparative 0.78 150 X X 0.0739 Example 1 Comparative 0.8200 Δ X 0.127 Example 2 Comparative 0.75 200 X X 0.0722 Example 3

TABLE 3 Refractive Exam- Exam- Exam- Exam- Exam- index ple 1 ple 2 ple 3Example 4 4 ple 5 ple 6 Region 1 1.502 1.505 1.498 1.491 1.511 1.505Region 2 1.35 1.349 1.321 1.346 1.211 1.375

As confirmed by Table 2 and FIGS. 10 to 15, the anti-reflective films ofExamples 1 to 6 exhibit one or more peaks at a scattering vector(q_(max)) of 0.0758 to 0.1256 nm⁻¹, in a graph showing the log value ofscattering intensity according to a scattering vector defined insmall-angle X-ray scattering, and as shown in Table 2, theanti-reflective films of Examples 1 to 6 can simultaneously realize highscratch resistance and anti-pollution properties while exhibiting lowreflectance of 0.70% or less in a visible light region.

As shown in FIGS. 1 to 6, it is confirmed that in the low refractivelayer of the anti-reflective films of Examples 1 to 6, hollow inorganicnanoparticles and solid inorganic nanoparticles are phase separated,most of the solid inorganic nanoparticles exist near the interfacebetween a hard coating layer of the anti-reflective film and the lowrefractive layer, and most of the hollow inorganic nanoparticles existat locations far from the hard coating layer.

As shown in Table 3, it is confirmed that the first region and thesecond region that are distinguished by the phase separation of thehollow inorganic nanoparticles and the solid inorganic nanoparticles inthe low refractive layer of the examples exhibit different ranges ofrefractive indexes, and specifically, the first region where solidinorganic nanoparticles are mainly distributed exhibits a refractiveindex of 1.420 or more, and the second region where hollow inorganicnanoparticles are mainly distributed exhibits a refractive index of1.400 or less.

To the contrary, as confirmed by Table 2 and FIGS. 16 to 18, in thegraphs showing the log value of scattering intensity according to ascattering vector defined in small angle scattering by the X-rayirradiation of the anti-reflective films of Comparative Examples 1 to 3,a peak does not appear at a scattering vector range of 0.0758 to 0.1256nm⁻¹, and such anti-reflective films of Comparative Examples 1 to 3respectively exhibit low scratch resistance and an anti-pollutionproperty as well as relatively high reflectance.

Further, as shown in FIGS. 7 and 9, it is confirmed that in the lowrefractive layers of the anti-reflective films of Comparative Examples 1to 3, hollow inorganic nanoparticles and solid inorganic nanoparticlesmixedly exist without phase separation.

What is claimed is:
 1. An anti-reflective film exhibiting one or morepeaks at a scattering vector (q_(max)) of 0.0758 to 0.1256 nm⁻¹, in agraph showing a log value of scattering intensity to a scattering vectordefined in small-angle X-ray scattering, wherein the small-angle X-rayscattering is measured by irradiating X-rays of a wavelength of 0.63 to1.54 Å to an anti-reflective film with a size of 1 cm*1 cm(width*length) at a distance of 4 m, wherein the scattering vector isdefined as in the following Equation 1:q=4π sin θ/λ   [Equation 1] wherein, in Equation 1, q is a scatteringvector, θ is a ½ value of a scattering angle, and λ, is a wavelength ofirradiated X-rays; wherein the anti-reflective film comprises a hardcoating layer and a low refractive index layer comprising a binderresin, and hollow inorganic nanoparticles and solid inorganicnanoparticles dispersed in the binder resin comprising a (co)polymer ofphotopolymerizable compounds, wherein the low refractive index layercontains 10 to 400 parts by weight of the hollow inorganic nanoparticlesand 10 to 400 parts by weight of the solid inorganic nanoparticles,based on 100 parts by weight of the (co)polymer of photopolymerizablecompounds, wherein the low-refractive index layer includes the hollowinorganic nanoparticles in a higher amount by weight than the solidinorganic nanoparticles, and wherein 70 vol % or more of the totalvolume of the solid inorganic nanoparticles exist within 50% of thetotal thickness of the low refractive index layer from the interfacebetween the hard coating layer and the low refractive index layer. 2.The anti-reflective film according to claim 1, wherein theanti-reflective film exhibits mean reflectance of 0.7% or less in avisible light wavelength region of 380 to 780 nm.
 3. The anti-reflectivefilm according to claim 1, wherein the solid inorganic nanoparticles aremore distributed than the hollow inorganic nanoparticles near theinterface between the hard coating layer and the low refractive indexlayer.
 4. The anti-reflective film according to claim 1, wherein 30 vol% or more of the total volume of the hollow inorganic nanoparticlesexist farther than the total volume of the solid inorganicnanoparticles, in the thickness direction of the low refractive indexlayer from the interface between the hard coating layer and the lowrefractive index layer.
 5. The anti-reflective film according to claim3, wherein 70 vol % or more of the total volume of the solid inorganicnanoparticles exist within 30% of the total thickness of the lowrefractive index layer from the interface between the hard coating layerand the low refractive index layer.
 6. The anti-reflective filmaccording to claim 5, wherein 70 vol % or more of the total volume ofthe hollow inorganic nanoparticles exist at a region exceeding 30% ofthe total thickness of the low refractive index layer from the interfacebetween the hard coating layer and the low refractive index layer. 7.The anti-reflective film according to claim 1, wherein the lowrefractive index layer comprises a first layer comprising 70 vol % ormore of the total volume of the solid inorganic nanoparticles and asecond layer comprising 70 vol % or more of the total volume of thehollow inorganic nanoparticles, and the first layer is positioned nearerto the interface between the hard coating layer and the low refractiveindex layer than the first layer.
 8. The anti-reflective film accordingto claim 7, wherein the first layer comprising 70 vol % or more of thetotal volume of the solid inorganic nanoparticles is positioned within50% of the total thickness of the low refractive index layer from theinterface between the hard coating layer and the low refractive indexlayer.
 9. The anti-reflective film according to claim 1, wherein thesolid inorganic nanoparticles have a density at least 0.50 g/cm³ greaterthan density of the hollow inorganic nanoparticles.
 10. Theanti-reflective film according to claim 1, wherein the solid inorganicnanoparticles and the hollow inorganic nanoparticles respectivelycontain one or more reactive functional groups selected from the groupconsisting of a (meth)acrylate group, an epoxide group, a vinyl group,and a thiol group on the surface thereof.
 11. The anti-reflective filmaccording to claim 1, wherein the binder resin included in the lowrefractive index layer further comprises a cross-linked (co)polymer offluorine-containing compounds comprising photoreactive functionalgroups.
 12. The anti-reflective film according to claim 11, wherein thefluorine-containing compounds comprising photoreactive functional groupsrespectively have a weight average molecular weight of 2000 to 200,000.13. The anti-reflective film according to claim 11, wherein the binderresin comprises, based on 100 parts by weight of the (co)polymer ofphotopolymerizable compounds, 20 to 300 parts by weight of thefluorine-containing compounds comprising photoreactive functionalgroups.
 14. The anti-reflective film according to claim 1, wherein thehard coating layer comprises a binder resin comprising a photocurableresin, and organic or inorganic fine particles dispersed in the binderresin.
 15. The anti-reflective film according to claim 14, wherein theorganic fine particles have a particle diameter of 1 to 10 μm, and theinorganic particles have a particle diameter of 1 to 500 nm.